Reprinted in The Best of What If? Followed by What If? #21. Alternate sequels appeared in What If? vol. 2, #35, and Paradise X: Heralds. This world was designated Earth-772 in Marvel Encyclopedia: Fantastic Four.

Spider-Man did eventually join as a member of the "New Fantastic Four" and more recently the Future Foundation.

Three different stories look at what would have happened if either Peter's class bully Flash Thompson, his would-have-been temporary girlfriend Betty Brant, and publisher J. Jonah Jameson's astronaut son, John, had been bitten by the radioactive spider instead. With the exception of Betty Brant, the protagonist dies in each story. A darker version of the Flash story is redone as What If? vol. 2, #76.

Presented as "untold history," it has been steadfastly relegated (at least, as written) to an alternate universe by Kurt Busiek and others. Designate Earth-9904 in All-New Official Handbook of the Marvel Universe: A-Z Update #2 (2007). A version of this timeline was revisited in Avengers Forever, and yet another version made a cameo in Paradise X: Heralds.

This issue examines the random decision for Richard Rider to become Nova and looks at how things might have changed if the powers of Nova had been transferred to a vengeful wife whose husband had been murdered, a kind, homeless black man in a universe with no superheroes, Peter Parker in a world where the radioactive spider had crippled him instead of giving him spider-powers and finally an unknown character with a villainous personality.

It was revealed years later that the clone had indeed lived, but had just been in hiding. He reappeared in the Spider-Man titles under the name Ben Reilly.

What if Wolverine had killed the Hulk? (Based on The Incredible Hulk #181)

The concept was reversed in What If? vol. 2, #50 (although it followed a later rematch between the characters). This issue also includes "What if the Fantastic Four had never been?" (based on The Fantastic Four #1). The latter world was designated Earth-8222 in Marvel Encyclopedia: Fantastic Four.

What if the Avengers had become pawns of Korvac? (Based on Avengers #177)

Reprinted in The Best of What If? A version of this world was visited by Quasar in Quasar #30.

This issue also includes "What if Yellowjacket had died?" (Based on Avengers #212)

What if the Fantastic Four had not gained their super-powers? (Based on The Fantastic Four #1)

Reprinted in The Best of What If? This version of the team reappeared in What If? vol. 2, #39. This world was designated Earth-8212 in Marvel Encyclopedia: Fantastic Four. This issue also includes "What if Richard Rider had not lost the power of Nova?" (Based on Nova #25)

The world featuring the Thing was designated Earth-8321 in Marvel Encyclopedia: Fantastic Four. This issue also includes "What if the Silver Surfer had lost the Power Cosmic?" (Based on Fantastic Four #50)

Select stories (noted above) were collected in a trade paperback, The Best of What If, in 1991. The entire series was collected in a series of seven volumes titled What If Classic from 2004 to 2010, with the exception of issues #13, #16, and the lead story of #43 because they featured licensed characters, namely Conan the Barbarian and Fu Manchu.

This world was designated Earth-9011 in Marvel Encyclopedia: Fantastic Four.

What if the Vision of the Avengers conquered the world? (Based on Avengers #254)

Two takes, one of which (a utopian world) was revisited in What If? vol. 2 #36. The utopian world was designated Earth-90110, and the dystopian world Earth-90111, in The Official Handbook of the Marvel Universe: Alternate Universes 2005.

Three different stories all related to the Cyclops-Jean Grey relationship, looking at what would have happened had Scott married Jean in the early days of the X-Men, if the pair had never gotten together and if Jean had married Wolverine instead. (Based on Amazing Adventures #11, Uncanny X-Men #1, and Uncanny X-Men #101)

What if... starring the Fantastic Four: The Thing... human again?! (What if Ben Grimm had stayed in Liddleville? Based on Fantastic Four #236)

This world was designated Earth-989 in Marvel Encyclopedia: Fantastic Four.

What if... starring The Uncanny X-Men: With Phoenix possessed... who will save Professor X... from the fury of Colossus? (What if Colossus had joined the USSR's Soviet Super-Soldiers? - Based on Giant Size X-Men #1)

Also includes... What if Doctor Doom had succeeded in conquering the world?

What if... starring Wolverine (What if Wolverine was a Horseman of War? - Based on Wolverine #100)

What if... starring Secret Wars: 25 years later... comes a new generation of heroes! (What if all the participants of Secret Wars had been trapped on Battleworld? - Based on Secret Wars #12)

Final issue. Written by Jay Faerber. This world was designated Earth-9811 in Marvel Encyclopedia: Fantastic Four.

Issue number "-1", What if... Starring Bishop (based on Uncanny X-Men #282), was published as a part of the "Flashback" event, in which most of Marvel's series published issues numbered "-1" that were set in the past.

The February 2006 one-shots took place in a single fictional universe, dubbed Earth-717 in previews, with four of the six stories more like DC's Elseworlds with various heroes in historical periods.[3]

What if Spider-Man had remained in 1980s Russia after an accidental death?

The series was also due to feature What If?: The New Fantastic Four, which featured the "original" New Fantastic Four with Spider-Man, Wolverine, Ghost Rider, and Hulk teaming up, as seen in Fantastic Four #347-349 and 374. This story was halted due to the passing of artist Mike Wieringo, and was released as a 48-Page Special as a tribute in June 2008. All the issues of this run, aside from the New Fantastic Four, were later collected into a trade paperback simply entitled "What If? Civil War". The version of the "New" Fantastic Four is also erroneous, as the Ghost Rider of that time period had been Danny Ketch, not Johnny Blaze, who appears in the issue instead for unexplained reasons (in reality, Wieringo had drawn the wrong Ghost Rider in his initial pages by mistake and it was not noticed until after his death).

This series continues the theme of alternatives for three recent Marvel events along with two around a classic event. The New Fantastic Four story was a sequel to the one-shot What If? released previously, seeing Iron Man replace Ghost Rider in an alternate take on the Infinity Gauntlet storyline. However, this series also features a storyline featuring the Runaways that runs though all five comics. This series was released between December 2008 and January 2009.

What If House of M - What if the Scarlet Witch had said 'No More Powers' instead of 'No More Mutants'?

At Fan Expo Canada '09, it was revealed a new five part What If series would be released, featuring five one-shots, each with two alternatives for the focused event, except for Daredevil vs. Elektra, which has only one story. As a back-up feature, in the four other one-shots, there's a humorous Say What? short story.

What If? Spider-Man: House of M

What if Emma Frost had not mindwiped Gwen Stacy?

What if Scarlet Witch had let Gwen Stacy and her son cross to the default reality and survive?

In early September 2010, Marvel announced a series of new What If? issues, including the celebration of the 200th issue of What If?.[4] It features a story regarding the Siege event, and a story by Stan Lee about the Watcher and Galactus. Further What If stories were released for Dark Reign, Spider-Man: Grim Hunt, a story focusing on Wolverine and his son Daken, and another on the pre-hero and villain lives of Iron Man and Doctor Doom. Those four issues also have a back-up story on Deadpool being controlled by the Venom symbiote.[5][6][7][8] The Venom/Deadpool backup chapters were subsequently released as a standalone one-shot.[9]

What If? Iron Man: Demon in an Armor

What if Tony Stark became Dr. Doom?

What if the Venom symbiote had managed to control Deadpool? (Back-up story, Part 1)

What If? Wolverine: Father

What if Wolverine had known about and raised Daken from birth?

What if the Venom symbiote had managed to control Deadpool? (Back-up story, Part 2)

What If? Spider-Man: Grim Hunt

What if Spider-Man had decided to kill Kraven the Hunter instead of letting him live?

What if the Venom symbiote had managed to control Deadpool? (Back-up story, Part 3)

What If? Dark Reign - The Osborn Assassination

What if Clint Barton had managed to kill Norman Osborn?

What if the Venom symbiote had managed to control Deadpool? (Back-up story, Part 4)

In July 2013 Marvel released a four-issue limited series for What If based on the 2012 event Avengers vs X-Men, telling the story of what might have happened if Magneto had been more influential in Hope's development for the Phoenix.

In April 2014 Marvel released a five-issue limited series for the 2013 event Age of Ultron, focusing on Wolverine and Invisible Woman's trip back in time to kill Hank Pym in order to prevent him creating Ultron and showing the effects for the Marvel Universe if one of the other four founding Avengers had died, or if Hank had simply elected not to create Ultron.

In October 2015, Marvel released a five-issue limited series for the 2013 event Infinity that depicted alternate outcomes for Thanos's invasion of Earth and the war with the Builders.[10] The five scenarios are the following:

Marvel released a new series of What If? one-shots in October 2018, which revived the concept of the publisher's classic series that examines alternate outcomes for famous storylines, and alternate versions of well-known characters in the likes of Spider-Man, Magik, Ghost Rider, Thor, the X-Men and the Punisher.